What do you guys think is the most valuable skill in indie filmmaking in terms of supply and demand? For example do you think it is acting or cinematography?
Depends on the budget level of your project, location, etc.
For example, finding strong actors can be very difficult if you're shooting a low budget project in a locale that doesn't have a film industry. Conversely, in LA or NY, you can find a ton of amazing actors.
Same goes with most positions. There's a lot of folks who call themselves cinematographers who aren't all that great, but there's also a ton who are amazingly talented too.
From experience, I would say the hardest positions to fill are:
Producer
1st AD
The reason why is these are the thankless jobs that every production needs but few really want to do. Especially 1st AD - your job is to run the set and keep it disciplined. You are to keep the director on track, yet the director is the boss on set (so you are managing your boss, which is never an easy task). You need to know how to be firm without angering everyone (and sometimes you will aggravate people, so you're skirting on the edge).
All the talent in the world on set (camera, acting, directing, prod design, etc) is useless if there's no one to keep things on schedule and on budget.
Same with marketing/publicity. These jobs (producing, 1st AD, publicity/marketing) aren't really artistic or technical positions, but administrative, and often the least attractive (which makes them the most in demand because comparatively fewer people want to do it compared to acting, directing, writing, camera, editing, music/sound, etc).